In recent years, the demand has increasingly grown for display devices including liquid crystal displays and plasma displays due to the start of digital terrestrial broadcasting and the spread of the internet and mobile telephones. Although some of these displays are mounted in mobile devices as compact displays, on the other hand, the demand for large-screen televisions also is growing.
In a conventional display, matrix interconnects are provided on a glass substrate; and particularly in the case of a liquid crystal display, thin film transistors are provided at the intersections of the matrix interconnects. Semiconductor manufacturing processes are used for the thin film processing. Therefore, when attempting to enlarge the display, it is necessary to use massive apparatuses based on semiconductor manufacturing processes; and the production line investments are enormous. Moreover, when the display is enlarged, the interconnect resistance increases because the interconnects lengthen; and problems occur because the transmission of the signals via the interconnects is delayed.
As a method for solving such problems, a display using a light guide structure has been proposed. This is a method to display an image by extracting light from any position of the light guide side surface by mechanically controlling the contact or the non-contact of a light extraction unit at the side surface of the light guide; and a display device having an efficiency higher than that of a liquid crystal display or a plasma display can be realized.
For example, in U.S. Pat. No. 5,953,469, an electrostatic force is used to cause a structural body for extracting the light to contact the light guide. An electrode is provided in the light guide; an electrode is provided also in the structural body opposing the light guide; and the structural body is caused to contact the light guide by causing an electrostatic force to occur due to the voltage difference between the two opposing electrodes (the electrode of the light guide and the electrode of the structural body). In the case where the voltage is not applied between the electrodes, it is necessary for the light guide and the structural body to be provided within a range in which the electrostatic force acts between the electrodes, that is, at an extremely small distance. Accordingly, it is desirable for the structural body to be disposed with high precision.
However, it is difficult to dispose many structural bodies uniformly with high precision.
Moreover, although it is necessary for the electrode provided in the light guide to be transparent for easy extraction of the light, the light is absorbed, albeit slightly, by transparent electrodes typified by ITO (indium tin oxide alloy) which is generally used. Therefore, the light extraction efficiency decreases because a part of the light inside the light guide is absorbed by the transparent electrode.